The long-term objective of this research program is to understand how infant mammals control their intake of milk in the natural suckling situation. This objective can be accomplished by investigating the appetitive, consummatory, and satiety phases of ingestion using in appropriate animal model. In reference to the satiety phase, the specific goals of this proposal are to determine whether the duration of paradoxical sleep is directly related to the volume of milk in the gut, and to determine if the vagal nerves and spinal nerves carry the volume- related satiety signals to the brain. This will be accomplished by recording electroencephalograms (EEG's), electromyograms (EMG's), and behaviors from suckling rats intubated with a known volume of rat's milk. Experimental subjects in section 2 will be denervated. Ultimately this research is designed to increase our understanding of the fundamental controls of ingestion in developing mammals, including humans. Several reports of sucking, ingesting, and sleeping in infant rats and humans suggest that they are very similar in many basic processes of physiology and behavior. Thus, the rat is a vital model for investigating suckling. A thorough understanding of the controls of suckling in the rat through invasive and non-invasive procedures will enable us to apply our knowledge to better the human condition. Obesity resulting from overingestion greatly increases the risk of diabetes mellitus, hypertension, and cardiac disorders. Identification of infants prone to obesity through the malfunction of an ingestive or satiety process would be a tremendous achievement in preventative medicine. lntervention during critical periods of growth with benign recording techniques, such as those developed in this proposal, may greatly increase our chance of preventing or it least decreasing the severity of obesity in our children.